Surah Al-Ma'idah, ayah 61

5:61

وَإِذَا جَآءُوكُمۡ قَالُوٓاْ ءَامَنَّا وَقَد دَّخَلُواْ بِٱلۡكُفۡرِ وَهُمۡ قَدۡ خَرَجُواْ بِهِۦۚ وَٱللَّهُ أَعۡلَمُ بِمَا كَانُواْ يَكۡتُمُونَ ٦١

Wa idhā jā'ūkum qālū āmannā waqad dakhalū bil-kufri wahum qad kharajū bihī wallāhu a'lamu bimā kānū yaktumūn

And when they come to you, they say, "We believe." But they have entered with disbelief [in their hearts], and they have certainly left with it. And Allāh is most knowing of what they were concealing.